1. Field of the Invention
This invention relates to novel coated films such as oriented polypropylene having good hot tack, and low blocking, together with satisfactory low temperature sealing and other properties.
2. Information Disclosure Statement Including Description of Related Art
The following information is being disclosed under the provisions of 37 CFR 1.56, 1.97 and 1.98.
Coatings comprising copolymers of ethylene and acrylic acid (EAA) have advantages over various previously used coatings, such as good low temperature sealing properties, water immersed seals, and resistance to crazing when flexed. However, when these coatings are applied to the sealable side of a base polymer film such as oriented polypropylene (OPP), it has been found in some instances that it would be desirable to have improved hot tack and blocking properties, particularly when the coated film is utilized on a relatively high speed packaging machine. Thus, any means to accomplish the foregoing improvements would be beneficial.
The following references may be pertinent to the invention disclosed herein.
U.S. Pat. No. 5,066,543 issued Nov. 19, 1991 to Hwo, teaches heat sealable wrapping or packing film capable of forming a peelable seal between substrates and comprising a blend of a copolymer of ethylene and an unsaturated carboxylic acid such as acrylic acid, a butene-1 homopoloymer or copolymer, and an ethylene homopolymer or an ethylene/unsaturated ester copolymer.
U.S. Pat. No. 5,126,198, issued Jun. 30, 1992 to Schinkel et al., discloses heat-laminatable multilayer films comprising a polypropylene base layer and at least one additional layer containing a mixture of an ethylene/vinyl acetate copolymer and an ethylene/acrylic acid copolymer.
U.S. Pat. No. 5,169,728 issued Dec. 8, 1992 to Murphy et al., discloses multilayered films wherein a "base" layer comprises a copolymer of ethylene and acrylic or methacrylic acid, and a "surface" layer comprises a copolymer of ethylene and a higher alphaolefin, i.e., a linear low density polyethylene (LLDPE).